Duncan Loop

The Duncan Loop, also widely known as the Uni Loop, is a uniquely versatile knot that gives anglers the ability to control whether their connection is a fixed snug knot or an open loop. When tied and left uncinched, the Duncan Loop creates an adjustable sliding loop that lets lures and flies swing freely for maximum action. When pulled tight against the hook eye, the same knot becomes a secure fixed connection. This dual nature makes the Duncan Loop one of the most practical knots in fishing. It is essentially the Uni Knot tied to a hook but left with an open loop instead of being snugged down, and it shares the Uni Knot’s reputation for reliability and ease of tying.

How to Tie the Duncan Loop

1. Pass the tag end of your line through the hook eye, leaving about eight to ten inches of tag end to work with.
2. Bring the tag end back toward the standing line and form a loop alongside the standing line. The tag end should be on top and the loop should overlap both the tag end and the standing line.
3. Wrap the tag end through the loop and around both the standing line and the inner leg of the loop. Make four to six wraps, working away from the hook.
4. Keep the wraps snug against each other and parallel. Pull the tag end to tighten the wraps into a neat column.
5. Moisten the knot and slide it toward or away from the hook eye to set your desired loop size. Pull the standing line to lock the knot at the chosen position.
6. Trim the tag end, leaving a small amount of extra line as a safety margin. The loop should be adjustable up until a fish puts serious pressure on the knot.

When to Use the Duncan Loop

• Lure fishing with open loop: Leave the loop open to give crankbaits, jerkbaits, and swimbaits unrestricted wobbling and darting action.
• Fly fishing streamers: Present streamers and baitfish patterns with natural movement by connecting them with an open Duncan Loop.
• Adjustable connection: Start with an open loop and let the first strike slide the knot tight if you prefer a snug connection under fighting pressure.
• All-purpose knot: Use it anytime you would use a Uni Knot but want the option of leaving an open loop for better lure presentation.
• Light tackle finesse fishing: Small jigs and soft plastics fished on light fluorocarbon benefit from the natural fall rate that a loop connection provides.

Pro Tips

• The number of wraps determines how easily the knot slides. Four wraps create a freely sliding loop, while six wraps make the knot grip more firmly at its set position. Choose based on whether you want the loop to adjust or stay put during use.
• If you want the loop to remain open during fishing, avoid pulling the standing line hard after setting the loop size. A gentle snug is enough to hold position. The loop will still close down under the pressure of fighting a fish.
• The Duncan Loop is identical in structure to the Uni Knot. If you already know how to tie a Uni Knot, you already know how to tie a Duncan Loop. Simply stop before cinching the knot tight to the hook eye.
• Retie the Duncan Loop after landing a fish that pulled the loop closed. Once the knot slides fully tight, it cannot be reopened without damaging the line at the knot, so start fresh for the next cast.

Pros and Cons

Pros:

• Adjustable loop size that can be set before fishing and slides tight under pressure
• Identical structure to the popular Uni Knot, making it easy for Uni Knot users to learn
• Simple to tie and forgiving of slight variations in technique
• Works as either an open loop or a fixed knot depending on how you finish it
• Effective on both monofilament and fluorocarbon across a wide range of line weights

Cons:

• The loop will slide closed under heavy fighting pressure from a large fish, so it is not a permanent open loop like the Non-Slip Loop Knot
• Not recommended for braided line, which is too slippery for the wraps to grip reliably
• Once the knot slides tight, you cannot reopen it and must retie for another open loop
• Slightly weaker than the Non-Slip Loop Knot for applications where a fixed open loop is needed
• The sliding nature adds a small element of unpredictability to loop size during aggressive hooksets